The VoIP technology enables voice communications through packet data based on an IP network such as the high-speed Internet, and is increasingly used as smartphones and the fourth generation mobile communications based on an IP such as Wi-Fi or LTE are spread.
In the VoIP service, it is important to transmit data at a predetermined interval for securing the service quality. However, when a VoIP service is used in a WLAN environment, it is difficult to constantly maintain a transmission interval of VoIP data due to scanning operations by a terminal and the characteristics of wireless data, and accordingly, the service quality may deteriorate.
According to the related art, jitter buffers are used to constantly maintain a transmission interval of VoIP data. A jitter buffer is generally installed in a wired or wireless client or a gateway, and the quality of a VoIP service is increased by reducing jitters generated on a network.